In recent years, one segment broadcasting, images for a personal computer application, and Web pages have been viewable on display sections of portable electronic devices. Thus, portable electronic devices have been prevailing which allow a housing with the display section to be rotated so as to place the display section in a horizontally long position.
Japanese Patent Laid-Open No. 2006-19925 discloses a portable information terminal including a first housing with an operation section, a second housing with a display section, and a rotational connecting mechanism connecting the first housing and second housing together so that the second housing slidably rotates with respect to the first housing. The rotational connecting mechanism disclosed in Japanese Patent Laid-Open No. 2006-19925 is configured to be shifted, by a rotational operation, a closed state or an open state to the other state; in the closed state, the second housing covers the entire operation section of the first housing, and in the open state, the second housing exposes the operation section of the first housing and becomes symmetric with respect to the center line of the first housing.
Moreover, Japanese Patent Laid-Open No. 2006-19925 discloses a rotational connecting mechanism shown in FIG. 1. The rotational connecting mechanism shown in FIG. 1 has first cam slot 201a and second cam slot 201b formed in bottom plate 2c of second housing 2, and first pin 202a and second pin 202b inserted through first cam slot 201a and second cam slot 201b, respectively. First cam slot 201a and second cam slot 201b are shaped like two circular-arcuate slots crossing each other. On the other hand, first pin 202a and second pin 202b are fixed to the surface of first housing 1. First flange portion 202c and second flange portion 202d are provided at the tips of first pin 202a and second pin 202b, respectively. First flange portion 202c and second flange portion 202d prevent first pin 202a and second pin 202b, respectively, from slipping out from cam slot 201.
With reference to FIG. 2, the operation of first housing 1 and second housing 2 connected together by the rotational connecting mechanism shown in FIG. 1 will be described. According to Japanese Patent Laid-Open No. 2006-19925, in the closed state, second housing 2 covers the entire operation section of first housing 1 (FIG. 2(a)). In the state shown in FIG. 2(a), second housing 2 is pushed up by the thumb of the right hand gripping first housing 1. Then, first pin 202a slides along first cam slot 201a. As a result, second housing 2 rotates clockwise around second pin 202b with respect to first housing 1 and shifts gradually with respect to first housing 1 (FIG. 2(b)). When second housing 2 is rotated clockwise by 90° with respect to first housing 1, the operation section (not shown in the drawings) of first housing 1 is exposed, and second housing 2 becomes laterally symmetric with respect to the center line of first housing 1. At this time, the portable information terminal is externally shaped substantially like the character “T” (FIG. 2(c)). Japanese Patent Laid-Open No. 2006-19925 states, in paragraph [0152], that first pin 202a and second pin 202b are fixed to the surface of first housing 1. Thus, the description, in Japanese Patent Laid-Open No. 2006-19925, that the “first pin 202a slides along first cam slot 201a” is expected not to mean that first pin 202a actually slides but that first pin 202a slides relative to first cam slot 201a. 